Some Native American tribes have been reported to have high rates of substance use disorders, including cannabis dependence (Mitchell et al. 2003; Gilder et al. 2006, 2007). In previous work with a Native American community, Ehlers and colleagues have found high rates of lifetime DSM-III-R cannabis dependence (43% for men, 24% for women) (Gilder et al. 2006) and have characterized some of the risk factors associated with cannabis dependence. Early cannabis use was found to be significantly associated with cannabis dependence (Ehlers et al. 2007). Unlike the general population, independent anxiety and affective disorders were not comorbid with cannabis dependence (Gilder et al. 2006). The aims of the present study were to: 1) further characterize cannabis dependence in this sample by subtyping the participants with cannabis dependence using cluster analytic techniques; 2) determine if those subtypes have differential heritability; and 3) conduct a linkage analysis of heritable subtypes of cannabis dependence.
